textproduct: Rapid City

KEY MESSAGES

- Beneficial rainfall expected through Sunday.

- Cooler temperatures for Sunday through Tuesday, then a gradual warm up for the rest of next week.

DISCUSSION

(This Afternoon Through Friday) Issued at 1106 AM MDT Sat Jun 20 2026

Current upper-air analysis and water vapor imagery depict weak troughing over the Great Lakes region with a shortwave positioned over southern ID/western WY and an upper low over southern AB. Satellite imagery indicates increased WV and cloud cover over WY and the NE panhandle. Radar returns show that some early thunderstorms have formed over south-central SD and central NE, with some light showers over east-central WY. Surface observations show temperatures mainly in the 60s to low 70s, with dew points in the 40s across northeast WY and 40s to low 50s across western SD. Winds are generally southeasterly at 10 to 20kts gusting to 30kts across northeast WY and western SD. Gusty southeasterly winds up to 40kts will continue to develop over the SD plains, with the strongest winds over northwest SD.

Confidence in severe weather today is currently mixed due to increased cloud cover over much of northeastern WY and western SD as the shortwave approaches. The 12z HREF run still suggests conditions will still be leaning towards a moderate chance for severe storms over northeast WY, the Black Hills, and into far southwestern SD. SPC has moved the slight risk out of the region, leaving just the marginal risk for northeast WY and southwestern SD. There is a 2% tornado risk and 5% severe wind and hail risk for those areas. A possible landspout can't be ruled out over northeast WY. Storms will continue to develop late this morning/early afternoon across northeast WY and south-central SD. Multiple rounds of storms are expected to move through northeast WY into western SD throughout the afternoon and evening. The first round of storms may wipe out the environment, resulting in weaker storms during the second round. We will have to wait and see if the environment will be able to recover. The best chance for severe weather will still be southeast WY into the NE panhandle where conditions are more favorable.

Thunderstorms and showers will continue to move through the region into the overnight hours and persist into Sunday as the shortwave continues to move across the region. Severe weather is unlikely. QPF values through Sunday evening are still trending towards at least 0.50" for most locations, with higher amounts east of the Black Hills, where 1.00" to 1.50" is not out of the question. Temperatures will be cooler Sunday with highs ranging in the 60s to low 70s. Winds will also be on the lighter side.

Next week will start off cooler and wet as a cold front pushes through, bringing another round of showers to the region. Chances for precipitation will continue throughout the week as temperatures gradually warm up by the end of the week.

AVIATION

(For the 18Z TAFS Through 18Z Sunday) Issued At 1102 AM MDT Sat Jun 20 2026

Expect gradually deteriorating conditions today as an upper level disturbance moves into the region. Moist southeasterly upslope flow will develop with stratus expected on the western SD Plains, especially near the Black Hills. Showers and thunderstorms are expected this afternoon and evening, with convection developing over WY and spreading east. More persistent showers are expected tonight into Sunday, especially across northwest South Dakota. Expect widespread stratus later tonight with IFR to local LIFR conditions.

UNR WATCHES/WARNINGS/ADVISORIES

SD...None. WY...None.